How to buy, grow and prune Wisteria ...

As I write this evening, the scent from my amazing Wisteria ‘Alba’ that now drapes over the back end of the house and comes all the way from the hot bed (where it is not yet fully in flower) is flooding into the kitchen through the open French doors. Yes, it is mingled with the scent of the Lonicera x americana that grows with it, but the overall, intoxicating perfume is Wisteria. It’s something one only experiences for around a month a year but it’s all the more special for that. And it looks amazing!

Wisteria floribunda 'Alba' across the South facing kitchen wall

I know some people who think Wisteria is a nasty, common, plant like Buddleja. I disagree on both. As well as being a plant lover I am a wildlife lover and both plants attract myriad insects by day and night. That’s great in my book. Yes, they can both get big and ungainly but only if you don’t know how to handle them. And they are so simple to control that no one should worry, even in a small garden. I have three Wisteria (one of each main type) and two Buddleja in a 60ft back garden and they all perform marvellously.

Others are terrified of Wisteria because of the supposed very specific pruning requirements. But the truth is that Wisteria is really easy to handle and prune if you just know a few basic facts.

I don’t normally write “How to..” type stuff in this blog but, given there’s poetry and allsorts already, I don’t really see why not when the need seems to be there. I have met so many people in the last few weeks who are not confident about growing Wisteria that I think it deserves a blog – because the truth is it is a very easy plant to grow and look after, and is wonderfully rewarding. I seek to de-bunk its scary reputation.

So, this piece is written to encourage those of you without a Wisteria to go out now and buy one, in the complete confidence that you will have it in flower, be able to control it and enjoy it for many years to come if you follow some simple advice. It could also be of value to those of you who have recently bought or inherited one but are unsure which it is or how best to care for it.

There are just a few basic things to understand about Wisteria and easy rules for buying and pruning it.

Things to know about Wisteria - types

There are three main different types of Wisteria in the UK:

1. W. sinensis (or Chinese Wisteria and also, somewhat unhelpfully, also known as W. chinensis). It is usually white or purple

2. W. floribunda (or Japanese Wisteria) which is supposedly somewhat less vigorous (though mine is not), has a slightly finer leaf, and comes in a range of colours from white through pink and purple to blue

3. W. brachybotrys (often called silky Wisteria) also usually white or purple. This has the finest leaves and often flowers a little later.

There are also any number of hybrids of all three types such as my purple W. sinensis ‘Caroline’. They all have slightly different flower raceme lengths and flowering months but you can be sure they will be flowering in April/May/June depending on where you are and where it is sited. There are ones with double flowers too but I don't think they have the grace of the single flowered varieties and are less insect friendly.

You will also come across W. Macrobotrys which is actually a W. floribunda with amazingly long (3-4 feet) flower racemes.

If you want the classically decorated front wall or back garden pergola, the ones to start with are either W. floribunda, W. sinensis or a hybrid of these.

Various Wisteria in my garden. W. floribunda 'Alba' top and bottom left, W. sinensis 'Caroline' top right and W. brachbotrys 'Schiro Kapitan Fuji' bottom right

Identifying Wisteria

To be entirely honest I was not sure whether my ‘Alba’ was a sinensis or a floribunda. I bought it very early, before I kept proper records. It started as a multi-stemmed bush version but has transformed into a vigorous climber as well.

One of the ways to tell the difference is that, if you look from above, floribunda twine clockwise and sinensis twine anticlockwise. For ages I thought mine was a W.sinensis but it twines clockwise and the racemes are now 16 inches (41 cms) long which probably makes it a W. floribunda! But it doesn’t matter because their pruning regimes are the same.

By the way, W. brachybotris also twine clockwise.

I love what I shall now refer to as my W. floribunda ‘Alba’. I think the long white flower racemes with their tiny, pale yellow centres are very distinguished. I also love the scent of my stubbier, purple W. sinensis 'Caroline'. Her shorter, bi-coloured pale violet and purple flowers work well on the swing seat where it would be inconvenient if they were any longer. Also she is particularly well scented during the day whereas the 'Alba' comes into its scented best in the evening.

I also have a W. brachybotris ‘Schiro Kapitan Fuji” which is bi-coloured very pale blue and white with a yellow centre and is much less vigorous than the other two and has flowers 15-20 cms long. It is not in flower yet.

Things to know about Wisteria - buds

All Wisteria have two types of bud, separately, on the same stems. The short, fat ones are flower buds. The long, thin ones are leaf buds. They are easy to tell apart, especially in February. This is key knowledge for pruning.

On all Wisteria except W. bachybotrys, they flower best on short sub branches coming off the main shoots – also key knowledge for pruning. They also flower along their branches but more sparsely.

The short spurs off which they flower best.

The sparser flowering along main branches

Things to know about Wisteria – position/shapes/size

All love sun. They prefer a South facing position, especially on a warm wall but will grow as standards, mushrooms, in pots, up trellises, will tolerate walls facing any direction except North, and grow through trees (less successful I think).

Generally, the shorter, wider and fewer the leaves on a spur the more vigorous and tall/long the plant will be. The shorter, more delicate Wisteria have more and thinner leaves per leaf spur. However, you need to check a well grown spur because they all start pretty thin and delicate.

Wisteria are incredibly hardy, tough as old boots once established, so don’t be shy or scared of them. They want to grow and expand and are hard to kill without a chainsaw.

Having said that, I am in mourning for a beautiful Wisteria across the road that gained a new owner and a “gardener” who clearly knows nothing about plants. He managed to stop it flowering so they took it out and he is now in the process of killing a beautiful, ancient, Clematis montana rubra. I am sorely tempted to intervene but have not yet plucked up the courage.

Anyway, if you follow these simple rules you will not fall into the same camp. Just take control of your Wisteria and don’t expect it to adorn your house, pergola or fence in year one. By year three you will be revelling in it and by year five you won’t believe how enormously it has grown, despite your pruning (see below). And it is horrifying how quickly year five comes! I am now in years four to ten with mine and it only seems a moment ago that I planted them.

When to buy Wisteria

Now, now, now - or at least any time from end April to end May, when they are in flower. Never buy a Wisteria that is not in flower or very well developed flower bud. Many can take seven years to flower so only ever buy one in flower.

Garden centres are always full of plants in flower and often this is the wrong time to plant them but the best time to enjoy them. However, Wisteria is different. Buying in season and in flower means you not only get to see the flowers, their colour and length and check their fragrance, it also means you are guaranteed flowers every year from hereon in - unless you mess it up.

So please don’t be tempted to buy one out of season that looks like a generously twining plant with lots of leaves and ‘buds’. The buds are probably leaf buds and you could be waiting for ever for it to flower, especially if it is a species variety. Indeed, if you planted one this year, last year or a few years ago which is still not in flower (or flower bud especially if it’s a W. brachybotrys which flower a little later), I urge you to dig it up, get rid of it today and buy one that’s in flower tomorrow. I promise you will thank me for this advice because it will flower every year from now until whenever, and after all, what's £30-£60 in comparison to seven years waiting?

If it has two or three of these on, or even a bit shorter, you're going to be OK

How to look after Wisteria

The only thing you really need to know is that they need lots of water while they get established – the first year or so. The old wives solution was to throw everything, old sink water, bath water etc on them and this is a good way to think about it. Keep watering in job lots as often as possible for the first two years. They are often planted beside walls for obvious reasons and wall bases are notoriously dry. Just keep throwing water at it in big clumps. Like most plants it’ll appreciate a good drench from a complete bucket/watering can/sink bowl or two, every few days, much better than a daily surface spray.

In my clay they need no feed after establishing (or watering really) so couldn’t be easier. They have found their own water lower down but if I am feeling generous they still get the odd dump of old water and sometimes some tomato feed but only when I remember – about once every two or three years! If you feed them with normal fertiliser you will get lots of leaf growth at the expense of flower growth. So don’t feed them or, if you feel you must, use a high potassium, low nitrogen feed like tomato food, sparingly. In lighter soils they’ll need more water, especially during dry periods.

What to grow it with

Their impact is probably best when they are on their own but I have purple Clematis ‘Daniel Deronda’ open in the home of my Alba, and pink and yellow Lonicera x americana amongst it on the kitchen wall. My purple W. sinensis 'Caroline' on the swing seat is flowering amongst white Clematis montana grandiflora and peachy orange Rosa ‘Crown Princess Margarita’. Fuji will flower later on the side arch with the roses.

Clematis 'Daniel Deronda' in the W. floribunda Alba at its multi stemmed source ie not yet fully in flower

Lonicera americana amongst Wisteria floribunda 'Alba'

Wisteria sinensis 'Caroline' on the swing seat with my first Rosa 'Crown Princess Margareta' flower of the year

How to prune Wisteria

If you don't prune Wisteria it'll be fine but will become uncontrollable and you'll lose flowers to leaf growth. Pruning is important to control the plant and to encourage flowers.

Wisteria needs proper pruning twice a year and usually quite a bit of controlling in between.

The first official prune is in August, after the flowers have gone and it has put on some major growth. This is really a 'tidying up' prune and it’s useful to think of it like this. You may want to do it earlier, for example if you live in London or a similar climate zone, and this is not a problem. Feel free and tidy it up. The plant will have grown lots of thin, whispy extensions which will be curling around all manner of other plants or climbing up your wall while it tries to extend itself in a major way. Wisteria don’t flower well along these shoots generally so the best plan is to curtail them anyway and let it extend more slowly, bit by bit, year by year. W. bachybotris is the only exception to this rule because it also flowers well along its stems.

Obviously you want it to spread, in a controllable way, so in August, approach each branch, tendril, spur with a pair of secateurs and cut them back to five buds-ish (including leaf buds), unless there is a major, thick branch you want to encourage. The reason for five buds at this time of year is that is harder to tell the flower and leaf ones apart. Sometimes, what you think is a leaf bud, will swell and come a flower one, so it’s safest to cut back to five or six now and do the final cut once the buds have swelled properly in February and you can tell them apart.

In Feb the next year the plant will have put on lots more growth since August and will need pruning again. You may also have had to control it in the months in between. I almost always do a further tidy up in November-ish because it insists on sending up tendrils everywhere and I have to get it out of nearby trees etc.. Feel free. Cut it back from where it shouldn’t be, get rid of those whispy tendrils and it’ll repay you. Just think 5-6 buds everywhere you want it to be and cut it right back where you don’t want it to be.

The February prune is the important one to encourage the flowering buds at the expense of the leaf buds which compete for energy as it grows. Feel free to tidy it generally and cut whatever back but take care with the side spurs. The general rule is to cut back to three flowering buds at this time. They are easy to spot now. They are short and plump. This pruning looks quite severe on the side spurs (often only a few cms) but is well worth doing and trust me.

And that’s it really, it’s as simple as that. All you ever needed to know about growing Wisteria successfully.

So, in summary: only ever buy it in flower; water lots to begin with; get to recognise flower buds from leaf buds; tidy it up a lot during the year thinking 5-6 buds and eventually cut it back to 3 fat flower buds on every side spur in February.

I'll do a "how to .." Wisteria pruning video later in the year. In the meantime, I wish you happy Wisteria gardening and lots of beautiful, magnificently scented, flower racemes.